This invention relates to a method for accessing pericardial space of the heart for delivery of medication or other therapy. It also relates to intravascular catheters for accessing the pericardial space of the heart.
The pericardium (also called pericardial sac or pericardial complex) consists of an outer fibrous layer and an inner serous layer. The fibrous pericardium is a flask-shaped, tough outer sac with attachments to the diaphragm, sternum, and costal cartilage. The serous layer is thin and is adjacent to the surface of the heart. For the purpose of this disclosure references to the pericardial membrane mean the fibrous pericardium and references to the pericardial space mean the space between the outer (fibrous) and the inner (serous) layers.
The pericardium serves as a protective barrier from the spread of infection or inflammation from adjacent structures. The distendable pericardial space produced by these layers normally contains approximately 20 cubic centimeters (cc) of fluid with electrolyte and protein profiles similar to plasma. Fluid serves as a lubricant to allow unimpeded motion of the heart inside the sack. Approximately 120 cc of additional fluid can accumulate in the pericardium without an increase in pressure. Further fluid accumulation can result in marked increases in pericardial pressure, eliciting decreased cardiac output and hypotension (cardiac tamponade).
Access to the pericardial space is desirable to provide a variety of cardiac therapies, including delivery of drugs or genetic agents, placement of electrodes, removal or infusion of fluid for diagnostic analysis or therapy, or other purposes. A variety of mechanisms have been developed for accessing the pericardial space, ranging from a simple puncture by a large bore needle to intricate catheter or cannula based systems provided with sealing and anchoring mechanisms.
Access to the pericardial space in the prior art has been disclosed as: piercing the pericardium from outside or inside the heart, and piercing the wall of a heart chamber. Prior mechanisms adapted to access the pericardial space by piercing the heart chamber include U.S. Pat. No. 5,797,870 issued to March et al, which discloses a catheter with a hollow helical needle to pierce the wall of a heart chamber. Particularly in the context of access to the pericardial space via the right atrium, it has been proposed that the transvenous catheter pierce the right arterial wall, as in U.S. Pat. No. 4,946,457 issued to Elliot and that the catheter pierce the right arterial appendage as in U.S. Pat. No. 5,269,326 issued to Verrier. Access to the pericardial space from the exterior of the body, accomplished by passing a cannula or catheter type device through the chest wall and thereafter passing the cannula or catheter through the pericardium into the pericardial space is disclosed in U.S. Pat. No. 5,827,216 issued to Igo, U.S. Pat. No. 5,336,252 issued to Cohen. These methods and mechanisms are not best suited to access the pericardial space without surgery and without piercing the wall of the heart so as to avoid danger of excessive bleeding.